Control system for generator having radio transmission feedback means

ABSTRACT

An electric generator system which includes a thyristor mounted within the generator rotor for controlling the field current, and a voltage regulator the output of which is coupled by means of a radio frequency transmitting unit to the generator rotor and fed into a combining unit. The combining unit additionally receives a signal from the exciter circuit as well as a third signal from a measuring unit. The measuring unit serves to continuously measure the current fluctuations in the exciter circuit. The output of the combining unit is fed to the gate of the control rectifier thereby regulating the current flow through the generator winding.

United States Patent CONTROL SYSTEM FOR GENERATOR HAVING RADIOTRANSMISSION FEEDBACK MEANS 1 Claim, 1 Drawing Fig.

U.S. Cl 322/27, 310/68 D, 322/73 Int. Cl 1102 9/30 Field of Search322/25, 27, 2s, 59, 73; 310/68 Primary Examiner-Otis L. Rader AssistantExaminerl-I. l-luberfeld Attorney-William K. Serp ABSTRACT: An electricgenerator system which includes a thyristor mounted within the generatorrotor for controlling the field current, and a voltage regulator theoutput of which is coupled by means of a radio frequency transmittingunit to the generator rotor and fed into a combining unit. The combiningunit additionally receives a signal from the exciter circuit as well asa third signal from a measuring unit. The measuring unit serves tocontinuously measure the current fluctuations in the exciter circuit.The output of the combining unit is fed to the gate of the controlrectifier thereby regulating the current flow through the generatorwinding.

BACKGROUND OF THE INVENTION This invention relates to an electricalgenerator control system, especially adapted for use with air and spacevehicles and includes a voltage regulator and a self-excited generator.The system includes controlled rectifiers mounted in the generatorrotor; and a radiofrequency transmitter and receiver are provided inplace of conventional brushes as further described in our correspondingUS. Pat. application Ser. No. 724,478 filed Apr. 26, 1968 and entitled,Electric Generator Control system. The illustrated embodiment providesthat the excitation of fluctuations sewing to provide voltage control beused to obtain the appropriate positive or negative additive voltage bymeans of thyristors. The purpose of this particular feature is theretention of a condition which exists prior to the load change andfurther to prevent the retention of either positive or negative voltagepeaks.

The illustrated embodiment achieves this object by including a measuringunit which continuously measures the current variations in the excitercircuit. The measuring unit applies a signal related to these variationsas an error signal to a combining unit. The second input to thecombination unit is the error signal obtained from the voltageregulator; and the third input is the constant voltage. The three inputsare processed to provide an optimal average voltage. The latter twoinputs are processed with each other to provide a voltage which determines the timing of the firing pulse for the thyristors. In this manner,reliability is considerably increased since coarse regulation takesplace prior to regulation by the main voltage regulator.

Other objects and advantages of the invention will become apparent withreference to the following description and accompanying drawing whichshows an illustrated embodiment of this invention.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a diagrammaticillustration of a generator system embodying certain features of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With respect to the FIGURE, whenthe load of the synchronous generator 111 varies, the exciter current inthe exciter winding 110 varies with the gradient in the load current.The reason for this occurrence lies in the retention of the excitationfield at the instant of load change due to the inductive characteristicsof the field winding. The current components in the exciter winding Iinvolved in the subsequent balancing processes are the induced current,the initial current prior to the load change and the current derivedfrom the voltage regulator. The invention, based on these conformitieswith natural laws, suggests that with a device as described in U.S. Pat.application Ser. No. 724,478, the exciter current, which provides aquantitative as well as qualitative measure of the disturbance in thebalanced condition at the instant of load change t=0, is used toeliminate the disturbance in balance. The condition occurs in rotor 113by measuring the exciter current. The measurement is performed by ameasuring unit 151, which, in this case, consists of a shunt and acurrent measuring means. The measuring unit comprises a shunt of thetype No. 1813-952, manufactured by the Hartman and Braun Company. Theso-called shunt may comprise a relatively high value lumped resistanceelement connected in parallel LII with the exciter current bus, thevoltage across the resistance element being proportional to the excitercurrent and hence reflecting variations and fluctuations in thiscurrent. The output of the measuring means is fed to a combining unit inwhich the timing components for the firing of the thyristors 152 arecombined. The combining unit is an adder with three inputs. An exampleof a unit suitable for use in this system is MC 1439 manufactured byMotorola. The timing components include a signal which produces the bestpossible averagle voltage value or all operating conditions, a voltage wich is derived from the signal regulator by means of the radiofrequencyunit 140 and which is dependent upon the actual voltage, and thepreviously described signal derived from the excitation current change.These three components produce the effective firing time angle or thefiring impulse which causes the thyristors to fire at the required time.An example of the signal or voltage regular suitable for use in thissystem is G 20-B92 of the AEG Company in Germany. The radiofrequencyunit includes a transmitter and receiver and suitable transmitting andreceiving antennas. These antennas may each comprise a standard dipoleantenna. The transmitter is an ordinary oscillator which is set for thetransmitting frequency, with a corresponding modulation stage, where theregulating signal is mixed in a known manner with a carrier signal. Inthe receiver, the regulating signal is again separated from the carriersignal by a demodulation stage and is transmitted in an amplifiedmanner. All these circuits are basic circuits and elements of radioengineering.

There are two primary advantages to be obtained by means of theillustrated embodiment. Firstly, there are substantially no timeconstants of any importance associated with the determination andstabilization of the regulator deviations; and secondly, the reliabilityof the generator system 120 or of the voltage control is improved byusing several regulation components.

Although only one specific embodiment of this invention has been shownand described herein, it will be understood that certain details of theconstruction shown may be altered without departing from the spirit andscope of this invention.

We claim:

1. The electrical generator system, particularly adapted for use withair and space vehicles, comprising a generator, an exciter, a commonshaft for mounting the armature winding of the exciter and the fieldwinding of the generator, a voltage regulating means connected to thestationary armature winding of the generator, controlled rectifier meansmounted within said common shaft for controlling the generator fieldcurrent, control means for controlling firing of the controlledrectifier means, radiofrequency means for coupling the output of saidregulating means to said control means, and comprising a radiofrequencytransmitter connected to said voltage regulating means and a receivermounted on said common shaft for receiving the output of saidtransmitter sensing means for sensing the fluctuations in excitercurrent and for producing an output signal in accordance therewith, andreference means connected to the exciter for producing a constantreference signal said control means including summing means including, afirst input connected to the output of said receiver, a second inputconnected to the output of said sensing means for summing the outputs ofsaid receiver, said measuring means and said reference means forproducing a resultant control signal for controlling firing of saidcontrolled rectifier means and hence controlling the generator fieldcurrent.

1. The electrical generator system, particularly adapted for use withair and space vehicles, comprising a generator, an exciter, a commonshaft for mounting the armature winding of the exciter and the fieldwinding of the generator, a voltage regulating means connected to thestationary armature winding of the generator, controlled rectifier meansmounted within said common shaft for controlling the generator fieldcurrent, control means for controlling firing of the controlledrectifier means, radiofrequency means for coupling the output of saidregulating means to said control means, and comprising a radiofrequencytransmitter connected to said voltage regulating means and a receivermounted on said common shaft for receiving the output of saidtransmitter sensing means for sensing the fluctuations in excitercurrent and for producing an output signal in accordance therewith, andreference meanS connected to the exciter for producing a constantreference signal said control means including summing means including, afirst input connected to the output of said receiver, a second inputconnected to the output of said sensing means for summing the outputs ofsaid receiver, said measuring means and said reference means forproducing a resultant control signal for controlling firing of saidcontrolled rectifier means and hence controlling the generator fieldcurrent.